Despite sharing the same camera module with the Galaxy S2, the Samsung Focus S can only shoot at a maximum resolution of 720p (in contrast to the S2's 1080p). On the plus side, it does a good job for only 720p.
For whatever reason, the default video setting is VGA (aka 640x480). We actually thought video recording was absolutely awful until we realized the mistake. Once we switch to 720p mode, we were rather impressed.
With the proper settings, videos come out crisp and bright, although in low light things get a bit grainy. Audio was impressive, picking up sounds cleanly from both behind and in front of the camera, though you don't get the option to record in stereo as with the HTC Titan.
We were also impressed with its ability to transition from bright to dark areas. It wasn't particularly fast at it, but it was very smooth. The frame rate was always equally as smooth.
There was a peculiar quirk we ran into involving the digital zoom during recording in that you can't. So long as you're not recording, you can zoom to your heart's desire, but as soon as you hit record, the option goes gray and you're stuck at whatever zoom level you started on.
It makes sense, considering that fiddling with zoom options while recording would make for a pretty bumpy video, but we'd still like to have the option.
In the end, the Focus S' recording capabilities are pretty good for being limited to 720p, and amongst other WP7 devices, we'd consider it one of the best.